Effect of estradiol implant on noradrenergic function and mood in menopausal subjects

The effect of the alpha 2-adrenoceptor agonist, clonidine, on plasma growth hormone (GH), plasma 3-methoxy-4-hydroxyphenylethylenegylcol (MHPG), blood pressure and sedation were studied in 16 menopausal subjects before and 6 wk after a 100-mg implant of estradiol. The specific binding of tritiated yohimbine to intact platelets also was studied. Estradiol implants increased basal GH output and reduced baseline MHPG and sedation scores. However, none of the subsequent responses to clonidine were altered. Platelet yohimbine binding also was unchanged following the implant. Both observer- and self-rating scales showed a marked reduction in anxiety and depression scores. The results suggest that estradiol may alter some indices of noradrenergic function, but that the mechanism does not involve alterations in alpha 2-adrenoceptor sensitivity.